Earlier quoted context omitted.
Google: "The rights you grant in this license are for the limited purpose of operating, promoting, and improving our Services, and to develop new ones." Dropbox: "You give us the permissions we need to do those things solely to provide the Services." I'm not sure there's any difference in intent or clarity here. I think it's clear that Dropbox is nicer about it. And because their product is smaller in scope maybe the…
What isn't clear in "promoting" the Services? Google can broadcast TV ads with your private photos if they want to.
But if you insist on reading the license that uncharitably, you have to accept that Dropbox too can find plenty of wiggle room to be evil. Seriously, you're granting "all needed permissions" without enumeration -- you don't find that scary? What if Dropbox decides that "providing the service" requires revenue gained from scraping credit card numbers from stored files? See? I can come up with equally silly scenarios.